Wood slicing machine



Aug. 28, 1956 D. E. BASS 2,760,533

woon SLICING MACHINE Filed June 10, 1955 x IO x 4 3%.

/ QAT- a QMEY/ United States Patent 2,760,533 wool) sucnso MACHINEDonald E. Bass, Rockford, Ill., assignor to Balsa Processing Company,Inc., Rockford, KL, a corporation of Illinois Application June 10, 1953,Serial No. 360,761

1 Claim. (Cl. 144-162) This invention relates generally to a woodslicing machine and, more particularly, to av machine in which a softwood such as balsa is sliced into thin sheets by a knife blade mountedto reciprocate into and out of engagement with a workpiece and having acutting edge spaced laterally from a metering board a distance equal tothe thickness of sheets to be cut. The metering board reciprocates withthe knife and limits the feeding movement of the workpiece after eachsheet is cut therefrom. To avoid crushing of the soft wood, it isdesirable to use a knife having a very sharp cutting. edge.

One object of the invention is to. construct a machine of the abovecharacter in a novel. manner to avoid dulling of the cutting edge of theknife and to insure that one sheet will be separated completely from.the workpiece during each reciprocation of the knife.

Another object is to avoid dulling ofv the knife blade through. theprovision of a yieldable material which supports the workpiece adjacentthe point where it is cut by the knife and which is mounted in a novelmanner to maintain the material out of contact with the metering board.

A further object is to pull each sheet away from the workpiece andbreak. any fibres holding the two together during the retractingmovement of the knife through the provision of novel gripping elementswhich permit movement of the sheet along the knife in the advance of thelatter but hold the sheet frictionally against reverse movement relativeto the knife during retraction thereof.

Other objects and advantages of the invention will become apparent from.the following detailed description taken in connection with theaccompanying drawings, in which Figure 1 is a fragmentary perspectiveview of a wood slicing machine embodying the novel features of thepresent invention, some of the parts being shown in section.

Fig. 2 is an enlarged fragmentary sectional view taken 2 In thedrawings, the invention is shown for purposes or illustration embodiedin a wood slicing machine of the type in which an elongated knife 19having a straight cutting edge 13 is reciprocated relative to and towardand away from a table Hand into and out of engagement with a workpiece13 on the table to slice :1 thin sheet 14 from one end portion of theworkpiece. In this instance, the table is stationarily supported as bya'suitable frame not shown) and has a hat horizontal top'15 defining awork supporting surface and terminating along one edge at a flatvetrically disposed end 16. The workpiece 13' is a generally rectangularblock having one flat surface resting onthe table top.

The knife 10- is a fiat elongated generally rectangular blade whosecuttingedge 11 extends longitudinally of the blade and is defined by theintersection of a flat side 17, and a hollow ground surface E8 of theblade. Tov prevent is: in its raised position.

crushing. of the workpiece 13 when the latter is a soft wood such asbalsa, the cutting edge 11 is made very sharp, the surfaces 1'7 and 18defining the edge in this instance intersecting. at. an angle of between14 degrees and 18 degrees. The knife is secured as by screws to anelongated horizontally disposed holder 19- which supports the knife in avertical' plane above the table 12 with the cutting edge 11 pointingdownwardly toward the table and disposed horizontally and parallel tothe flat table end 16.

Supporting the knife 10' and its holder 19 for reciprocating movementrelative to the table 12 is an elongated slide 21 connected rigidly atits opposite ends to the knife holder by bolts 22. The slide is suitablymounted for reciprocation of the knife in a vertical plane and back andforth between a raised position spaced above the workpiece as shown inFig. 3 and a lower position (see Figs. 1 and 2) in which the cuttingedge 11 engages the table top 15 along a line parallel to. and spacedfrom the flat table end 16. Such mounting of the slidev 21 may comprisestationary guides (not shown which are received in straight parallelslots 23 formed in the slide. To obtain a broad- Wise movement of theknife toward and away from the table 12 so that the cutting, edge 11passes through the workpiece 1'3 with a slicing action, the guide slots23, While lying in. a vertical plane, are inclined away from thevertical at an angle of approximately 35 degrees. With this mounting ofthe slide 21, the cutting edge 11 is shifted back and forth horizontallywhile it reciprocates in a vertical plane and maintains itsparallelrelation with the table top 15. Reciprocation of the slide and the knifemay be effected in any suitable manner as by a crank or hydraulicactuator whose. stroke may be adjusted to vary the stroke of the knife.

During the advance of the knife 10 toward the table 12 the workpiece 13"is held against movement relative to the table top 15 by a veiticall'yreciprocable clamping member 24 which is suitably mounted forreciprocationverticall'y into and outof engagement with the workpieceand which is raised in timed relation toand after retraction of theknife to its-raised position to permit the workpiece to be advanced.under the knife and toward the flat tableend 16. Such advance may be'eifected in any suitable manner as by a pressure bar 25' engaging therear end of the workpiece and acting under continuous pressure derivedfrom springs or the like to urge the work continuously toward the fiattable end 16.. As the knife descends in its advancing movement, theclamping member 24 isactuated to hold the workpiece against the tabletop;

Feeding movement of the workpiece 1-3 is limited by a flat elongatedmetering board or stop member 26 which reciprocates vertically with theknife 10 and back and forth across the Hat table end 16 and which ispositioned below the knife to project above the table top 15 and engagethe workpiece as shown in Fig. 3 when the knife in this instance, theboard is mounted on the knife: slide 21 through the medium of guides 27rigid with: the slide. and slidably receiving two spaced.horizontalguide rods: 28 secured at opposite ends to arms 29 projectingrigidly from the side of the board opposite the table. With thisconstruction, movement of the board may be. limited to verticalreciprocation while the knife 10 andv the knife slide 21 shifthorizontally,

endwise movement of the board being prevented by rollers equal to thedesired thickness of sheets to be cut, herein approximately of an inch.If desired, the work engaging surface of the board may be covered with athin sheet (not shown) of stainless steel to facilitate movement of thissurface across the adjacent end of the workpiece 13.

To prevent dulling of the knife cutting edge 11 resulting from itsengagement with the table top 15, it is desirable to support theworkpiece 14 adjacent the flat table end 16 on a strip 32 of yieldableand preferably resilient material such as rubber which the cutting edgeenters as shown in Fig. 2 in the lower position of the knife. spreadsthe yieldable material thereof laterally of the knife and toward theclosely adjacent reciprocating metering board 26 which, when it contactsthe yieldable material, tends to curl and break off the edge of thelatter due to the friction and relative movement between the two.

In accordance with one aspect of the invention, the strip 32 ofyieldable material is mounted in the table 12 in a novel manner to avoidthe foregoing difficulty and permit the use of the material where, as inthe present instance, the spacing between the cutting edge 11 and thereciprocating metering board 26 is very small. This is accomplished byinterposing between the strip and the metering board a very thin plate33 of material, preferably metal, which is harder than the yieldablestrip 32 and maintains the latter out of engagement with the meteringboard. To insure that the cutting edge 11 of the knife always engagesthe strip of yieldable material, the metal plate 33 is made much thinnerthan the spacing between the cutting edge and the board and herein isfrom .032 to .040 of an inch thick. The plate extends along and definesthe upper part of the fiat table end 16 and, along its upper edge,defines the edge of the table top 15 and provides a rigid backing foreach sheet being cut.

It has been found in service use that the strip 32 of yieldable materialrequires frequent replacement. To facilitate such replacement, the stripand the metal plate 33 are formed as parts of a removable backing unit34 which fits into a recess 35 of right angular cross section cut intoand extending along the flat table end 16. In the form shown in Fig. 2,this unit 34 comprises a wooden rectangular base 36 adapted to fit intothe bottom of the table recess 35, the plate 33 which is secured to oneside of the base 36 by screws 37 and projects above the base, and thestrip 32 of yieldable material which is a rectangular block of rubberbonded to the plate and the base and flush on its outer surface with thetop edge .of the plate and the fiat table top 15 to constitute a part ofthe latter. The unit is suitably secured to the table 12 as by screws(not shown) threaded into the base 36 and extending upwardly through theunderside of the table. In this instance, the plate 33 is made of ametal such as brass which is softer than the steel work engaging surfaceof the metering board 26 so as to avoid scratching this surface. Therubber strip 32 is one quarter of an inch thick.

If desired, the backing unit 34 may be constructed as shown in Fig. 3with two of the metal plates 33 disposed parallel to each other andextending along opposite sides of the unit to enable the latter to bereversed to provide a new section of the yieldable strip 32 for theknife cutting edge 11 when the portion of the strip adjacent one of theplates becomes worn. In this instance, the two plates are the parallelleg portions of a channel 38 of U-shaped cross section filled with theyieldable material 32 molded in the channel and bonded to the innersides of the metal plates. To strengthen the bottom wall of the channelfor attachment to the table 12 as by screws 39, a thin steel plate 41lies along the bottom wall between the latter and the yieldablematerial. In this form of backing unit, the channel walls are each .032of an inch thick, the yieldable material 32 is rubber one quarter of aninch thick,

Such entry of the cutting edge into the strip '4. and the bottom plate41 is made of steel one eighth of an inch thick.

When the cutting edge 11 of the knife 10 is protected by a yieldablebacking material as described above, it has been found that some sheets14 being cut from the workpiece 13 remain attached to the latter afterthe cutting movement of the knife by a few fibers which are pushed intothe backingand thus are not completely severed by the cutting edge. As aresult, the sheet being cut, instead of moving upwardly with theknifeand the metering board 26 in the retracting movement of the knife,remains against the table top 15 and prevents feeding movement of theworkpiece toward the metering board.

In accordance with another aspect of the invention, complete severanceof each sheet from the workpiece 13 is insured by frictionally grippingeach sheet 14 in a novel manner and pulling the same away from theworkpiece in the upward movement of the knife 10 and the metering board26. For this purpose, gripping elements 42 are mounted on the meteringboard 26 and project toward the knife and to a position spaced from thelatter a distance less than the thickness of each sheet 14. The grippingelements 42 are yieldably urged toward the knife to clamp each sheetagainst the latter and prevent downward movement of the sheet relativeto the knife while permitting the sheet to pass upwardly between theelements and the knife.

In this instance, the gripping elements 42 are the free squared ends ofa series of-flat spring fingers 43 fixed as by screws at their otherends to the metering board 26 at spaced points along the latter and eachprojecting upwardlytoward the hollow ground knife surface 18. The'latterfaces downwardly toward the metering board and cooperates with the boardto define achannel through which each sheet 14 being cut advances in thedownward movement of the cutting edge 11 through the workpiece 13. Theintermediate body portions of the fingers are curved inwardly from themetering board toward the knife 10 to position the free ends 42 closelyadjacent the ground knife surface 18 and provide tensioning meansyieldably urginglthe free ends toward the knife. The force exerted bythe spring fingers 43 on the free gripping ends 42 is sufficient toclamp each sheet 14 against the knife to prevent reverse movement of thesheet downwardly along the knife while permitting these gripping ends tomove outwardly away from the knife for movement of each sheet upwardlyalong the latter. When the knife shifts horizontally relative to themetering board 26 during vertical movement of the two together, thesheet and the outer ends 42 of the fingers 43 tend to shift horizontallywith the knife as permitted by the'flexibility of the fingers.

During downward movement of the knife 10 and metering board 26 in theoperation of the machine, the workpiece 13 is held stationary againstthe table top 15 by the clamping member 24 and the cutting edge 11slices from the workpiece a sheet 14 equal in thickness to the spacingbetween the cutting edge and the metering board. This sheet movesupwardly relative to and along the hollow' ground knife surface 18 andbetween the latter and the free ends 42 of the spring fingers 43 aspermitted by flexing of the fingers outwardly away from the knife. Asthe knife reaches the bottom of its stroke, the cutting edgeenters theyieldable strip 32 and tends to spread the latter. toward the meteringboard. Due to the confining action of the metal plate 33, however, thestrip isprotected from contact with the board.

As the knife 10 and metering board 26 move upwardly relative to thetable 12,'the free ends 42 of the fingers 43 hold the sheet against andin frictional engagement with the adjacent knife surface 18 so that thesheet is pulled away from the workpiece 13 to break any fibres stillconnecting the two and not cut by the knife. When the knife and theboard reachytheir upper positions, the clamping member. 24 is releasedand the workpiece is permitted to slide along the table top 15 towardand into abutting engagement with the board under the action of thepressure bar 25. As the knife begins to descend out before the cuttingedge engages the workpiece, the clamping member 24 is actuated to holdthe workpiece against the table top 15. The sheet 14 just cut off isretained between the knife and the gripping finger ends until the knifebegins its next advancing movement and then is engaged by the upper edgeof the next sheet which forces the preceding sheet upwardly and out frombetween the knife and the finger ends. The freed sheet may then betransferred away from the machine either manually or by a conveyormoving behind the metering board.

I claim as my invention:

In a wood slicing machine, the combination of a table having a flat worksupporting surface, an elongated flat metering board extending along andmounted to reciprooate back and forth across one end of said table in aplane extending transversely of said fiat table surface, a knife mountedto reciprocate with said board in a plane parallel to said plane ofboard reciprocations and having a straight cutting edge disposedparallel to and spaced from the side of said board adjacent said tableand movable toward and away from the table during reciprocating movementof the knife to cut ofi sheets from the end portion of -a workpieceadvanced along said table surface and into engagement with said board,each of said sheets passing between said board and said knife during thecutting operation, and a plurality of spring fingers secured to saidboard at spaced points along the latter and projecting from the boardtoward said knife and to positions spaced from the knife shorterdistances than the spacing between said cutting edge and said board toengage each sheet passing between the board and the knife and hold thesheet frictionally against the knife whereby the sheet is pulled awayfrom the workpiece in the retracting movement of the knife.

References Cited in the file of this patent UNITED STATES PATENTS958,395 Helm May 17, 1910 1,123,386 Russell Jan. 5, 1915 1,815,670Haworth July 21, 1931 2,007,731 Tomlin July 9, 1935 2,532,672 MichaelDec. 5, 1950 2,592,782 Zweifel Apr. 15, 1952

